Frozen Shower head

How do I get a frozen shower head off? It will not turn with a pipe wrench and I am afraid I will break the pipe.

Two pipe wrenches and someone with great upper body strength.

If the same person is handling both wrenches, with handles close to each other, the side forces are essentially balanced and you shouldn't break the pipe. You may mess up the chrome finish on the pipe coming out of the wall.

Now if you are talking about the pipe coming from the wall, then there is a good chance you will break something internally if it was not installed with the outlet elbow attached to the framing.